what would happen if you formed a 1" to 2" high triangular ridge on the hearth support slab, shaped so the edge closest to the oven is verticle and it slopes outward, this ridge would be 6" outside of the outer edge of the wall forming a circle and will be used later on to reinforce the first row of soldier bricks.

Then insulate the hearth 2+ inches trimming the floor and insulation to the same circle. Then form and place a 1" thick x 4" ring of vermicrete to insulate your wall bricks. Place your first wall row on top of (outside and against the top 1" of the hearth bricks) of the vermicrete ring. Set your first row of soldier bricks. Now place vermicrete beveled between the top edge of the first soldier course and your circular ridge, since vermicrete is strong in compression and allows for a little flex would this support the walls of a low dome oven without causing stress cracks?

The dome could still be insulated conventionally the hearth support slab would have to be a little larger, you could use the same base support and the foundation slab would be a little larger.

Justin

11-14-2008 01:42 AM

Re: bracing low dome ovens

i lost you at "if you formed a 1" to 2" high triangular ridge". can you show it in a diagram?

dlgeis

11-15-2008 07:11 PM

Re: bracing low dome ovens

2 Attachment(s)

Justin

Here are two poor pictures the first shows a cross section through the hearth with a small ridge formed to the right and vermicrete angled from the dome down to that ridge, triangle ridge shown but square or rectangle would also serve to leave something for vermicrete to purchase to.

The second is a top view. The center circle is the dome then the next circle is the vermcrete reinforcement and the next ring is the ridge formed in the top of the hearth for the vermicrete to but up against.

If these photos are not clear enough I can get a better camera and try again next week. I'm kind of high tech chalenged.

Doug

dmun

11-15-2008 07:44 PM

Re: bracing low dome ovens

Here's a thought: Insulation board is very strong in compression. What if you built your buttressing as a ring around the dome, bracing it against the exterior masonry enclosure? Not the cheapest solution since the board isn't cheap, nor does everyone do structural masonry at or above slab level. It would be well insulated, and insulation board is easier to cut than masonry.

Wiley

11-15-2008 09:43 PM

Re: bracing low dome ovens

I think I understand what you're trying to do. Buttress the dome. On a dome the force vectors push outward and downward at the base and the shallower the dome the more outward the vectors. Historically large domes were/are supported by means of a large chain which runs the circumference at the base. That won't work because of the break, the opening entrance. Large domes of course being complete circles at their base. The low dome ovens I've seen pictures of all seem to be made in massive structures rather unlike the free standing dome self supporting dome of the Pompei Oven. The massive structures supplying/being the buttress.

I think what you describing would work although some mechanical connection of the buttress to the support might be desireable rather than just relying upon the ridge to hold the vermicrete. Maybe large bolts. Also you might consider segmenting the buttress so that differential expansion would not be a problem. Cathedrals used thinner buttresses (later these butresses became arches and became the "flying buttresses" we all know) so there is less of a need for the buttresses to be one continuous member all around the dome. Maybe something in the way of radial wedges, each with their own bolt.

Unless you were going for a low dome look (as opposed to hiding the dome in a gabled structure) I would think it might be easier to cast a concrete retaining wall (where your planned ridge would be) and build the dome over a form and fill the space between the dome and the retaining wall with vermicrete. This is sort of a play on what dmun is suggesting.
Hope this is some help,
Wiley